Impression control mechanism automatically selecting one of a plurality of cams



3,239,049 ISM AUTOMATICALLY SELECTING ONE OF A PLURALITY OF CAMS Original Filed June 27, 1962 March 8, 1966 w. F. VOlT, JR

IMPRESSION CONTROL MEGHAN 2 Sheets-Sheet 1 INVENTOR.

WILLIAM F. VOIT JR.

BY ,f eadak (7 ATTORNEY.

March 8, 1966 I w, vo -r, JR 3,239,049

IMPRESSION CONTROL MECHANISM AUTOMATICALLY SELECTING ONE OF A PLURALITY OF CAMS Original Filed June 2.7, 1962 2 Sheets-Sheet 2 FIG. 2

United States Patent IlVIPRESSION CONTRdL MECHANISM AUTOMAT- ICALLY SELECTING ONE OF A PLURALITY 0F CAMS William F. Voit, Jr., Lexington, Ky., assignor to International Business Machines Corporation, New York, N.Y., a corporation of New York Continuation of application Ser. No. 205,784, June 27,

' 1962. This application Sept. 3, 1963, Ser. No. 305,920

5 Elaims. (Cl. 197-16) This application is a continuation of a prior application Serial No. 205,784, filed June 27, 1962, and having the same title as the present application, now abandoned.

This invention relates to typewriters and more particularly to print impression control mechanisms for type- Writers.

The invention has particular utility in a typewriter of the type disclosed in US. Patent 2,919,002, L. E. Palmer, Selection Mechanism for a Single Printing Element Type- -writersame assignee as the present application.

The aforementioned patent describes a machine which has a single element printing head wherein all the characters of a type font are located on the surface of the single head.

A character is selected by tilting and rotating the single element printing head in response to depression of one of a plurality of keylevers, each keylever being assigned to a character on the printing head. The keylevers selectively actuate a displacement mechanism having two principal portions, one for tilting and another for rotating the printing head. More specifically, selecting links are operated which determine the pivot points of connecting members to produce an output of predetermined displacement and direction. In each portion of the displacement mechanism, the value of the output is determined by the links selected either singly or in combination. When the links are selected in combination, the displacement is the sum of the individual displacements of the links. A tape and pulley mechanism couple the displacement mechanism to the printing head to, locate the selected character in a reference position. Thereafter, the head is caused to strike the platen to print the chosen character.

In the typewriter of US. Patent 2,919,002, all characters on the typehead impact upon the printed page at approximately the same velocity and consequently, have about the same print blow. The machine is adjusted to print the majority of the characters with the proper impression, the result being the small face area characters, such as the punctuation characters, may impress the paper harder than desired, with the possibility of paper penetration and side printing.

Therefore, an object of the invention is to provide a mechanism for controlling velocity of a print element in a typewriter.

Another object of the invention is to provide a mechanism for controlling impact of a single element typehead during a print operation.

An additional object of the present invention is to provide an impression control mechanism for a typewriter which is selectively operable according to the character selected for printing.

In order to accomplish these and other objects of the invention, an impression control mechanism of simplified design is provided which is automatically operable under control of a typewriter selection mechanism and which controls the degree of print head force generated according to selections made.

The foregoing and other objects, features and advan tages of the invention will be apparent from the following more particular description of the preferred embodiment of the invention as illustrated in the accompanying drawings.

In the drawings:

FIGURE 1 is a diagrammatic representation of a typewriter.

FIGURE 2 is a detailed representation of a print control mechanism according to the invention.

Single element typewriter In order to facilitate an understanding of the present invention, a diagrammatic representation of a typewriter like that disclosed in US. Patent 2,919,002, is shown in FIGURE 1.

The typewriter of FIGURE 1 has a spherically shaped type head 101 which has a plurality of characters embossed thereon, and which is mounted on a rocker platform 102, that is pivotally mounted on a rocker shaft 103. The head 101 is first selectively tilted and rotated in order to position a desired character for printing and is then subsequently actuated against a paper 104 that is positioned against a platen 105 to effect printing of the character selected.

The actuation of the print head 101 occurs when the rocker platform 102 is rocked about its shaft 103 during a print cycle following the depression of a keylever that is associated with the character desired. Only one keylever, that is keylever 106, is shown in FIGURE 1. It will be understood that a suflicient number of keylevers will ordinarily be provided to select all characters on the print head 101.

A motor 107 continuously drives a shaft 108 by means of apulley 109 and belt 110. The shaft 108 is selectively coupled to a cycle shaft 1111 through a clutch mechanism 112, which is like that described in the aforementioned US. Patent 2,919,002. The clutch mechanism includes a helical spring, not shown, which is normally retained in an unwound condition under control of a clutch sleeve 113 and clutch latch 114 which engages a step 115 on the sleeve 113.

Actuation of the print head occurs in the following manner:

Assuming that it is desired to print the character that is associated with keylever-106, the typist depresses keylever 106 by means of a keybutton 116'.

The keylever i106 is pivot-ally mounted on a fulcrum rod 117. Pivotally mounted on a stud 118, is a keylever pawl 119 which is maintained in a rest position by a spring 120. The pawl 119 extends below the keylever 106 and is formed to strike an interposer 121.

vInterposer 12 1 is slidably mounted for movement from right to left in FIGURE 1 on a fulcrum rod 122, as well as up and down in a guide comb, not shown. A spring 123 maintains the interposer 1:21 in a rest position.

Depression of keylever 106 and pawl 119 results in movement of interposer 121 from its rest position. Movement of the interposer 121 results in a rotation and tilting of head 101 as described in the aforementioned Palmer patent, through the medium of selector bails, not shown.

The interposer 121, as well as the other interposers that would normally be provided, has several lugs extending downwardly therefrom. Certain of the lugs control the head selection function. Another lug 124 operates against a cycle bail 125 to move it downwardly. The bail 125 through link 126, causes pivoting of latch 114 which releases the clutch sleeve 113. Release of sleeve 113 result-s in actuation of clutch 112 and rotation of cycle shaft 111.

The cycle shaft 111 rotates 180 during each print cycle, and through gears 127, 128, and 129 causes a 180 rotation of a filter shaft 130.

i The filter shaft 130 is a two-bladed shaft which is positioned just below the ends of all interposers, such as end 131 of intenposer 121. The shaft 130 engages a step 132 on interposer 121 and during rotation forces interposer 121 forwardly to operate the character selection mechamsm.

Description of impression control mechanism The print impression control mechanism of the present invention is shown in detail in FIGURE, 2, where print elements corresponding to those of FIGURE 1 are given like reference numerals. These elements include the filter shaft 130, rocker platform 102, interposer 121, and print head 101. Another interposer 201 has been positioned alongside interposer 121.

Pivotally mounted adjacent the leftmost extremities of interposers 121 and 201 is a vane 202. Vane 202 has notches 203 and 204 and solid portion 205 and 206 in a predetermined arrangement opposite the interposer extremities.

Vane 202 has an associated collar arm 207 that is pivotally attached to a link 208. Link 208, in turn, is pivotally attached to a cam follower latch 209. Latch 209 has an arm 210 which engages a formed car 211 on an impression control cam follower 212. Latch 209 and follower 212 are pivotally mounted at 213 and 214, respectively.

Follower 212 has a formed upper extension 215 that normally rests on a lobe 216 of a cam 217. Cam 217 is fixedly mounted on the filter shaft 130.

Attached to a lower extension of follower 212 is a cable 218 which is movably enclosed in a sheath 219. Cable 218 is routed to a plate 220 where the sheath portion 221 is rigidly aflixed by means of a clamp 222, but not so rigidly that movement of cable 218 is restricted.

The uppermost extremity of cable 218 is attached to an arm 223 which pivotally mounted at 224 on plate 220.

The arm 223 engages a collar 225 of a concentrically mounted sleeve 226 that is slidably mounted on a shaft 227. Afiixed to shaft 227 is a concentrically mounted collar 228. Mounted between collar 225 and collar 228 is a compression spring 229 which tends to maintain sleeve 226 to the right on shaft 227.

The rocker 102 is driven from a print shaft 230 which is rotatably mounted adjacent the rocker 102 and which drives the rocker 102 either by means of a low velocity cam 231 or a high velocity cam 232, under control of the impression control mechanism just described.

Extending from the sleeve 226 are two forked arms 233 and 234 which control the positioning of a cam roller 235 on a shaft 236. The shaft 236 is mounted in a forked arm 237 which pivots about a pivot shaft 233. The arm 237 has a groove 239 which slidably engages a stud 240 on the rocker 102.

The cams 231 and 232 are differently cut as can be observed in FIGURE 2 in order to impart a different velocity to the roller 235 and associated mechanism depending on which cam drives the roller 235.

As mentioned, the sleeve 226 and its associated arms 233 and 234 are normally positioned to the right and, as a consequence, the roller 235 is also positioned to the right under cam 232.

Positioned underneath the grooved end of arm 237 is an adjustable stop screw 241 which extends upward from a threaded base 242. Arm 237 is positioned under control of screw 241 so that a slight clearance exists between roller 235 and cam 232 when the mechanism is in the home position.

Under proper conditions, the sleeve 226, and its associated arms 233 and 234, are slidably moved to the left so that roller 235 is then positioned opposite the cam 231. Cams 231 and 232 are preferably cut so that if a slight clearance exists between cam 232 and roller 235 when the aforementioned adjustment is made, a similar slight clearance will exist between earn 231 and roller 235, thus eliminating frictional contact between the cams and roller 235 at rest, and facilitating movement of roller 235 with respect to the cams.

Operation of impression control mechanism In order to illustrate the operation of the impression control mechanism, it will first be assumed that interposer 121 is depressed. It will further be assumed that interposer 121 is associated with a character that requires a normal amount of impressive force during the print cycle.

In FIGURE 2, it will be observed that the left extremity of interposer 121 is opposite the notch 203. When interposer 121 moves to the left during the print cycle as a result of rotation of the filter shaft 130, the left end of interposer 121 will pass through the notch 203.

As a result, the vane 202 remains in its normal rest position, the cable 218 is not actuated and roller 235 remains in position under the high velocity cam 232. A normal high velocity will then be imparted to the rocket platform 102 and print head 101.

It will now be assumed that interposer 201 is associated with a character such as period comma or similar character which requires less velocity during printing.

When interposer 201 moves to the left iin response to depression of its associated keylever, the left extremity of interposer 201 will engage the solid portion 205 of the vane 202. Vane 202 then pivots counterclockwise and pulls cam follower latch 209 counterclockwise, thereby releasing the cam follower 212. At this time a slight clearance exists between arm 210 of latch 209 and ear 211 of follower 212 so that no load is exerted on the interposers by the print impression control elements. Follower 212 is then able to drop off the stepped lobe 216 of cam 217 and follow cam 217 during the print cycle.

As a consequence, cable 218 is drawn to the left and through arm 223, moves sleeve 226 in a leftward direction against compression spring 229. Movement of sleeve 226 and its associated forked arms 233 and 234 results in the positioning of cam roller 235 under the low velocity cam 231.

When the print shaft 230 and cam 231 are rotated during the print cycle, the coaction between the cam 231, roller 235 and associated arm 237 will impart a lower velocity to the rocker 102 and print head 101.

The arrangement of drive mechanism and selection mechanism is exemplary, and other arrangements could readily be employed. For example, the mechanism could be arranged to normally impart a low velocity to the print head 101 rather than a high velocity as shown, with movement of the vane 202, cable 218, and roller 235 imparting a high velocity print action.

The interposers, such as interposers 201 and 121, could have extremities of different length for engagement with vane 202, thereby imparting varying degrees of movement to vane 202 and latch 209. Additional differently cut cams, cam followers, and associated cables with arms like arm 223, could be provided along with cam 217, follower 215, and cable 218. More than two cams could be provided on shaft 230 with the roller 235 being selec tively positioned adjacent any cam by appropriate move.- ments of the respective cables and associated arms.

It is apparent that a novel and simple mechanism. 19

been provided which insures proper control of print element velocity, and which is automatically and selectively controlled in an eflicient manner.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes inform and detail may be made without departing from the spirit and scope of the invention.

What is claimed is:

|1. An impression control mechanism for printing apparatus, comprising:

a platen, said platen normally supporting a document for printing;

a printing element;

means mounting said printing element for movement from a rest position to a printing position against a supported document, said mounting means including a cam follower;

a plurality of key-actuated selecting mechanisms, each of said mechanisms having an associated interposer that is movable from a home position to an active position;

means operable under control of said selecting mechanisms for positioning said printing element in order to select individual characters to be printed;

print drive means, said print drive means being actuated in successive print cycles, and said print drive means further having a plurality of drive cams for imparting respectively different degrees of driving force;

a print impression control mechanism including a common member selectively operable under control of said interposers for coupling a predetermined one of said cams to said cam follower;

and primary drive means automatically operable during each cycle to control said positioning means to select a character and concurrently with character selection to actuate said print impress-ion mechanism to determine the velocity imparted to said printing element during subsequent printing of the character selected.

2. An impression control mechanism for printing apparatus, comprising:

a platen, said platen normally supporting a document for printing;

a printing element;

platform means mounting said printing element for movement from a rest position to a printing position against a supported document;

a plurality of individual key-actuated means;

means operable under control of said key-actuated means for positioning said printing element in order to select individual characters to be printed;

print drive means, said print drive means being operable in successive print cycles, and said print drive means further having a plurality of drive cams for imparting associated varying degrees of driving force;

a cam follower, said cam follower being attached to said platform and normally positioned adjacent a first one of said drive cams in order to be driven by said first drive cam during a print cycle and thereby impart a velocity to said print element that is dependent upon said first drive cam;

a print impression control mechanism operable under control of said key-actuated means for retaining said cam follower in its normal position or for positioning said cam follower adjacent a different one of said drive cams;

and primary drive means automatically operable during each cycle to control said positioning means to select a character and concurrently with character selection to actuate said print impression mechanism to determine the velocity imparted to said printing element during printing of the character selected.

3. A print control mechanism for a typewriter having 6 a platen and a document positioned thereon for printing, comprising;

a printing element having a plurality of embossed characters, said element 'being mounted for movement along a path adjacent said platen, and said element 'further being mounted for reciprocable movement during successive print cycles from a rest position away from said document to a printing position against said document;

key actuated interposer means;

means controlled by said interposer means for positioning said printing element in order to select individual characters to be printed;

print drive means for driving said printing element from its rest position to its printing position in order to effect printing of a selected character;

a print impression mechanism including a common vane member and a normally latched cam member controlled by said interposer means 'for selectively controlling the velocity imparted by said print drive means to said printing element so that a predetermined degree of impression is obtained [for each char- 1 acter selected;

and primary drive means automatically operable during each cycle for actuating said interposer means to control said positioning means for selecting a character for printing and concurrently with character selection to actuate said print impression mechanism dependent on the character selected to determine the velocity imparted to said printing element during subsequent printing in the same cycle.

4. An impression control mechanism for a typewriter,

comprising:

a printing element having a plurality of embossed characters, said element being movable from a rest position to a printing position against a document to be printed;

means operable in successive print cycles for positioning said printing element in order to select individual characters to be printed;

a cyclically and automatically operable print impression control mechanism including a common drive member for establishing predetermined degrees of velocity of said printing element during said print cycles, and according to the individual characters selected;

a key actuated mechanism for selectively controlling said positioning means and said print impression control mechanism;

and drive means operable during successive cycles to actuate said positioning means for selecting a character and concurrently with character selection to actuate said print impression mechanism to thereby determine the velocity imparted to said printing element during printing of the character selected.

5. A velocity control arrangement for printing apparatus, comprising:

a platen, said platen normally supporting a document (for printing,

a printing element;

means mounting said printing element for movement from a rest position toward a supported document;

key-actuated means;

first drive means, said first drive means being operable in successive cycles under control of said key-actuated means and having a plurality of drive elements for imparting respectively different predetermined degrees of velocity to said printing element;

a printing control mechanism, said printing control mechanism including a common actuating member for selectively controlling the coupling of said drive elements in said first drive means;

and a second drive means under control of said key actuated means and automatically operable during each cycle of operation :for actuating said printing 7 8 control mechanism to selectively couple one of said 2,825,440 4/1958 Bauder et al. 19717 drive elements in said first drive means in order to 3,014,569 12/1961 Palmer 197-16 thereby select a particular driving velocity for said printing element just prior to operation of said first References Cited y the Applicant drive means in each individual cycle of operati n- 5 UNITE STATES PATENTS R f db th 1,652,463 12/1927 Tyberg.

e erences Cite Y e Examme' 2,796,966 6/1957 Toeppen.

UNITED STATES PATENTS 2,750,022 6/ 1956 Long 197-47 ROBERT E. PULFREY, Primary Examiner. 

1. AN IMPRESSION CONTROL MECHANISM FOR PRINTING APPARATUS, COMPRISING: A PLATEN, SAID PLATEN NORMALLY SUPPORTING A DOCUMENT FOR PRINTING; A PRINTING ELEMENT; MEANS MOUNTING SAID PRINTING ELEMENT FOR MOVEMENT FROM A REST POSITION TO A PRINTING POSITION AGAINST A SUPPORTED DOCUMENT, SAID MOUTING MEANS INCLUDING A CAM FOLLOWER; A PLURALITY OF KEY-ACTUATED SELECTING MECHANISMS, EACH OF SAID MECHANISMS HAVING AN ASSOCIATED INTERPOSER THAT IS MOVABLE FROM A HOME POSITION TO AN ACTIVE POSITION; MEANS OPERABLE UNDER CONTROL OF SAID SELECTING MECHANISMS FOR POSITIONING SAID PRINTING ELEMENT IN ORDER TO SELECT INDIVIDUAL CHARACTERS TO BE PRINTED; PRINT DRIVE MEANS, SAID PRINT DRIVE MEANS BEING ACTUATED IN SUCCESSIVE PRINT CYCLES, AND SAID PRINT DRIVE MEANS FURTHER HAVING A PLURALITY OF DRIVE CAMS FOR IMPARTING RESPECTIVELY DIFFERENT DEGREES OF DRIVING FORCE; A PRINT IMPRESSION CONTROL MECHANISN INCLUDING A COMMON MEMBER SELECTIVELY OPERABLE UNDER CONTROL OF SAID INTERPOSERS FOR COUPLING A PREDETERMINED ONE OF SAID CAMS TO SAID CAM FOLLOWER; AND PRIMARY DRIVE MEANS AUTOMATICALLY OPERABLE DURING EACH CYCLE TO CONTROL SAID POSITIONING MEANS TO SELECT A CHARACTER AND CONCURRENTLY WITH CHARACTER SELECTION TO ACTUATE SAID PRINT IMPRESSION MECHANISM TO DETERMINE THE VELOCITY IMPARTED TO SAID PRINTING ELEMENT DURING SUBSEQUENT PRINTING OF THE CHARACTER SELECTED. 